Sources and apportionment of aliphatic hydrocarbons in freshwater fish species from Shatt Al-Arab River, Iraq

Abstract

Aliphatic hydrocarbon n-alkanes, pristane (Pr), and phytane (Ph) were determined in the tissues of sixeconomic freshwater fish species (Luciobarbus xanthopterus, Ctenophyngodonidella, Cyprinus carpio, Tilapia zillii, Palanizaabu, and Leuciscus vorax) collected from the Shatt Al-Arab river. They were analyzed bycapillary gas chromatography - flame ionization detector (GC-FID). The carbon chain lengths of n-alkanesin the fish tissue samples ranged from nC13 to nC36. The highest concentration of the total n-alkanes wasdetected in the filter feeder P. abu tissue (23.14μg/g dry weight) and the lowest concentration was in theomnivorous C. carpio tissue (3.76 μg/g dry weight). The major sources of the n-alkanes, pristanes, andphytanes were from petroleum hydrocarbons based on the results of the molecular biomarker indices andthe ratios of CPI (carbon preference index), Pr/Ph, LMW/HMW (total nC13-C24/total nC25-nC36), nC17/Pr,and nC18/Ph. The percentage of n-alkanes from petroleum related-products ranged from 83.2% to 94.8%,whereas the natural biogenic sources were in the order of bacterial (3.7-11.7%) > higher plant wax (0.0-9.1%) > algal (0.1-1.2%) sources. The occasion of high fractions of n-alkanes and isoprenoids from petroleumhydrocarbons in these fish tissues indicated that the foster habitats were highly contaminated by crude oil.Further studies are required to investigate the bioaccumulation of other anthropogenic contaminants suchas plasticizers, pesticides, and polycyclic aromatic hydrocarbons fresh-water organisms.